Grounded voltage protection circuit for a linear drive circuit

Abstract

A grounded voltage protection circuit for a linear drive circuit includes an AC-DC power supply module, a first voltage protection module, an LED module, a drive IC and a linear current adjustment module. Through the cooperation of the first voltage protection module, the drive IC and the linear current adjustment module, when a DC voltage signal output by the AC-DC power supply module exceeds a first preset voltage value, the first voltage protection module outputs the first preset voltage signal to prevent the drive IC and the LED module from being damaged due to the overvoltage output by the AC-DC module, and avoid the transient impulse voltage in the entire voltage protection circuit, thereby enabling the voltage protection circuit to pass the CEC certification.

What is claimed is: 
     
       1. A grounded voltage protection circuit, comprising:
 an alternating current to direct current (AC-DC) power supply module configured to obtain an alternating current (AC) input voltage and convert the AC input voltage into a direct current (DC) voltage; 
 a light emitting diode (LED) module comprising at least one LED string; 
 a first voltage protection module electrically connected to the AC-DC power supply module and the LED module, respectively; 
 a drive integrated circuit (IC); and 
 a linear current adjustment module electrically connected to the LED module; 
 wherein the first voltage protection module is configured to output a first preset voltage when the DC voltage exceeds the first preset voltage, and the first voltage protection module is configured to output the DC voltage when the DC voltage does not exceed the first preset voltage; 
 the LED module is configured to receive the DC voltage output by the first voltage protection module to light the at least one LED string; 
 the drive IC is electrically connected to the AC-DC power supply module, the first voltage protection module and the linear current adjustment module respectively, and is configured to output a reference voltage and a control signal to the linear current adjustment module; 
 the linear current adjustment module is configured to adjust and control an output current of the LED module according to the reference voltage and the control signal; and 
 the grounded voltage protection circuit further comprises a second voltage protection module, wherein the second voltage protection module is electrically connected to the linear current adjustment module and the LED module respectively, and the second voltage protection module is configured to output a second preset voltage to the linear current adjustment module to protect the linear current adjustment module when a voltage of a negative electrode of the LED module exceeds the second preset voltage. 
 
     
     
       2. The grounded voltage protection circuit of  claim 1 , wherein the LED module comprises one LED string. 
     
     
       3. The grounded voltage protection circuit of  claim 1 , wherein the LED module comprises a first LED string and a second LED string which are connected in series. 
     
     
       4. The grounded voltage protection circuit of  claim 3 , wherein the second voltage protection module comprises a second varistor; one end of the second varistor is electrically connected to the linear current adjustment module and the LED module respectively, and the other end of the second varistor is grounded. 
     
     
       5. The grounded voltage protection circuit of  claim 4 , wherein the first voltage protection module comprises a fast recovery diode and a first varistor; a positive electrode of the first fast recovery diode is electrically connected to the AC-DC power supply module, and a negative electrode of the first fast recovery diode is electrically connected to a positive electrode of the first LED string and one end of the first varistor respectively; and the other end of the first varistor is grounded; and
 the second voltage protection module further comprises a third varistor; one end of the third varistor is electrically connected to a negative electrode of the first LED string and a positive electrode of the second LED string, and the other end of the third varistor is grounded. 
 
     
     
       6. The grounded voltage protection circuit of  claim 1 , wherein the second voltage protection module comprises a transient voltage suppression diode; a positive electrode of the transient voltage suppression diode is connected to the LED module, and a negative electrode of the transient voltage suppression diode is grounded. 
     
     
       7. A grounded voltage protection circuit, comprising:
 an alternating current to direct current (AC-DC) power supply module configured to obtain an alternating current (AC) input voltage and convert the AC input voltage into a direct current (DC) voltage; 
 a light emitting diode (LED) module comprising at least one LED string; 
 a first voltage protection module electrically connected to the AC-DC power supply module and the LED module, respectively; 
 a drive integrated circuit (IC); and 
 a linear current adjustment module electrically connected to the LED module; 
 wherein the first voltage protection module is configured to output a first preset voltage when the DC voltage exceeds the first preset voltage, and the first voltage protection module is configured to output the DC voltage when the DC voltage does not exceed the first preset voltage; 
 the LED module is configured to receive the DC voltage output by the first voltage protection module to light the at least one LED string; 
 the drive IC is electrically connected to the AC-DC power supply module, the first voltage protection module and the linear current adjustment module respectively, and is configured to output a reference voltage and a control signal to the linear current adjustment module; 
 the linear current adjustment module is configured to adjust and control an output current of the LED module according to the reference voltage and the control signal; and 
 the first voltage protection module comprises a first fast recovery diode and a first varistor, wherein a positive electrode of the first fast recovery diode is electrically connected to the AC-DC power supply module, and a negative electrode of the first fast recovery diode is electrically connected to the LED module and one end of the first varistor, and the other end of the first varistor is grounded.